Telephone system.



o. W MUKIBBBN. TELEPHONE SYSTEM. APPJIOATION FILED JULY 29, 1909.

1 ,004,290, Patented Sept. 26, 1911.

CHARLES W. MCKIBBEN, OF BEAUMONT, TEXAS.

TELEPHONE SYSTEM.

Speccation of Letters Patent.

Patented Sept. 26, 1911..

Application filed July 29, 1909. Serial No; 510,255.

To all whom it may concern:

Be it known that I, CHARLES W. MCKIB- BEN, a citizen of the United States, residing at Beaumont, in the county of Jefferson and State of Texas, have invented certain new and useful Improvements in Telephone Systems', of, which the following is a specification.

My invention relates to improvements in telephone systems, and has for its general object to provide an effective telephone set i and circuits therefor for use in transmitting over a'very high impedance line.

On long iron-wire lines, for example, where the impedance ractically precludes the use of ordinary te ephone instruments,

' my invention finds `advantageous employfor the transmitter, and a large induction coil, 8. lIn the, use of such devices, however, it will be obvious that if the receiver of the speaking party received the full eiect of the hlgh potential current which is necessarily employed to transmit to a distant arty, the

' effect upon the speakers ears wou d be unbearable, whereas if the receiver were wound to stand such current without producing abnormal sounds as a result, the waves transmitted from the opposite end of the hi h impedance line would not sutliciently agect the receiver to be intelligible.

In the operation of the invention, therefore, I provide a system whereby both highly efficient transmitters and high power inducately proportione tion coils may be employed in conjunction with very sensitive receivers and yet without producing unpleasant etl'ect in the ears of a s eaking party. To this end I provide for t e interposition in the receiver branch of the circuit of an im edance device appropril and referably, disabling means for the .impe ance device, arranged in conjunction withl means forhpotentiating the transmitting devices in such a way that when the transmittin devices are potentiated, the impedance device is likewise potentiated for operation; and-vice versa.

Specifically, 10 and 10 represent the line wires, bridged by branch 11, including the secondary of the induction coil 8, and bridged also by a receiver branch 12, including the two receivers 6, 6, and having connected therein an adjustable. impedance'device such as the coil 13, adjustedl or opened by switch 13. The transmitter circuit 14 includes the battery 7, transmitter 5, and primary of the induction coil. A shunt 15 1s thrown around the impedance device and acts as a disabling means for the impedance device. ,In the shunt 15 and the transmitter circuit 14, and, preferably, the branch 11 as well, controlling switches are provided so combinatively arranged that as the circuit branch 15 is opened, circuit branches 14 and 11 are closed; and vice versa. Such switch, as illustratedin Fig. 2 may comprise the movable contacts 11, 14 ,and 15', associated in common with an operating handle 16 in such relation to their stationary contacts 11, 14, and 15, that the contacts 15 and 15"l stand normally made while the other two are broken, and pressure upon the handle `v16 will reverse this condition,` opening contacts 15', 15, and closing the others. Now it will be ap arent that whenever a party desires to yta k, he must press upon the handle 16 to close the transmitter circuit as also, in the embodiment shown, the bridge 11, to potentiatehis transmitting devices, and such action automatically opens the low-impedance shunt 15 around the impedance coil 13 cutting said impedance device in series with the receivers. Thus the receivers are protected from such abnormal response as would be damaging or unpleasant to the ears of the talking party. When the partys transmit-ter is not in use, however,l and he is being talked to, he releases his key, thereby breaking his branch circuit 11 and transmitter circuit 14, and closing the disabling shunt 15 around the impedance device, 1 3, so that his receiver may be subjected to the maximum eii'ect of the current on the line transmitted from the distant point. In brief, the transmission from remote points is received directly; from the 'lamine station, it is afected by the impedance evice. 

